From the ballistic and destructive effectiveness standpoint, the gun s.I.G.33 was judged to be outstanding. Due to the short range and poor mobility of the towed gun, it rarely got into action during attacks. Before the first 15 cm s.I.G.33 (Sfl.) auf Pz.Kpfw.I Fargestellt has been tested in combat in May 1940, the Waffenamt was already engaged in development of an improved model based on the Pz.Kpfw.II chassis. On its wheeled carriage, the S.I.G.33B was mounted too far to the rear. Firing resulted in the Pz.Kpfw.II unacceptably tipping backward. Without wheels on the carriage, the s.I.G.33 could be mounted considerably farther forward, which was significantly advantageous for stability of Pz.Kpfw.II when firing. Since the room inside the standart Pz.Kpfw.II was unacceptably small, a lengthened and widened hall was made. Additional space for fighting compartment was also achieved by mounting engine transversely across the rear. A transfer case mounted in the right rear redirected power forward through a drive shaft which ran along the right side to the transmission and transverse mounted Pz.Kpfw.II steering unit. Unlike the normal Pz.Kpfw.II suspension, a sixth road wheel was added to the lengthened chassis. A trial series of 12 S.I.G.33B (Fl.) was ordered from Alkett for delivery starting in August 1941. Being months behind the schedule, Alkett finally completed seven S.I.G.33B (Sfl.) in December 1941, five in January 1942
The vehicles, organized in two independent companies were sent to Africa Corps in Libya to take part in the intended attack on Tobruk. S.I.G.33B (Sfl.) were engaged in the major offensive Operation Venezia. Combat experience immediately revealed the engine weakness and many other design faults, aggravated by African conditions. The greatly overloaded vehicle immediately overheated and was too un maneuverable. The vehicles were reported as having been lost by 2 December 1942. The British reported capturing six of them abandoned during the withdrawal, all in a dismantled condition in tank workshop
Being an effective weapon gun s.I.G.33, has very poor mobility, being towed, and rarely got into action during at tasks. In 1941 a trial series of 12 s.I.G.33 on widened and lengthened Pz II sasses was released. The vehicles were sent to Africa Corps in Lubia. They were engaged in the major offensive Operation Venezia. In African conditions these greatly overloaded s.p.g. immediately overheated and were too un maneuverable. All had been lost by Desember 1942